In recent years, liquid crystal display devices have been made larger, and there has been a tendency toward a growing demand for large liquid crystal display devices. However, cost reduction is required for further widespread use. Accordingly, there has been a growing demand for cost reduction in color filters, for color filters are high in cost ratio. In particular, it is important to raise yields, for yields directly affect costs. Accordingly, there has been a growing demand for the accurate detection of defects in color filters.
Conventional examples of methods for manufacturing color filters include a staining method, a pigment dispersion method, an electrodeposition method, and a printing method. However, each of these methods requires repetition of the same step for putting colors red, blue, and green. The large number of steps causes a decrease in yield and an increase in cost of liquid crystal displays.
Proposed in view of this is an ink-jet method for forming a color filter by discharging a color filter member onto a transparent substrate with use of an ink-jet head. The ink-jet method makes it possible to form red, blue, and green in one step, and therefore makes it possible to bring about a drastic cost-reducing effect such as simplification of manufacturing steps.
However, since the ink-jet method uses the ink-jet head, the color filter member is in liquid form. This makes it necessary to dry the color filter member discharged onto the transparent substrate. In the step of drying the color filter, the color filter starts to dry at the periphery thereof. This makes it difficult for the color filter to be uniform in shape across the substrate, thus causing a change in shape mainly near a boundary between the color filter and a black matrix. It is this change that causes slight unevenness of luminance.
Proposed in view of this is an inspection method for extracting a defect by conducting various inspections at the time of production of a color filter after a drying step, an example of which method is a technique, relating to detection of a defect such as a minute foreign body on a color filter, which detects a foreign body by illuminating a color filter from directions different between an outward movement of the color filter and a homeward movement of the color filter, by imaging diffuse reflected light, by converting a pattern of steps in the outward movement and the homeward movement into binary data, and by taking cognizance through a logic operation AND (Patent Document 1).    Patent Document 1: Japanese Unexamined Patent Application Publication No. 20065/1995 (Tokukaihei 7-20065; published on Jan. 24, 1995)